Hello, Anne Gentle (annegentle). 
Could you help me to confirm about this issue, please?
Here is my confirmation procedure. Please FYI.

===command===
$ neutron net-create hogehoge --router:external True
Created a new network:
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | True                                 |
| id                        | d9eb9f00-dc2c-4fbf-89e9-70a79641e91d |
| name                      | hogehoge                             |
| provider:network_type     | vxlan                                |
| provider:physical_network |                                      |
| provider:segmentation_id  | 1002                                 |
| router:external           | True                                 |
| shared                    | False                                |
| status                    | ACTIVE                               |
| subnets                   |                                      |
| tenant_id                 | e8ca6431d808494a839de2f18a26f10c     |
+---------------------------+--------------------------------------+

$ neutron subnet-create hogehoge 192.168.1.0/24
Created a new subnet:
+-------------------+--------------------------------------------------+
| Field             | Value                                            |
+-------------------+--------------------------------------------------+
| allocation_pools  | {"start": "192.168.1.2", "end": "192.168.1.254"} |
| cidr              | 192.168.1.0/24                                   |
| dns_nameservers   |                                                  |
| enable_dhcp       | True                                             |
| gateway_ip        | 192.168.1.1                                      |
| host_routes       |                                                  |
| id                | be1d5068-ded7-4cbd-92d6-126a1bd771a8             |
| ip_version        | 4                                                |
| ipv6_address_mode |                                                  |
| ipv6_ra_mode      |                                                  |
| name              |                                                  |
| network_id        | d9eb9f00-dc2c-4fbf-89e9-70a79641e91d             |
| tenant_id         | e8ca6431d808494a839de2f18a26f10c                 |
+-------------------+--------------------------------------------------+

$ neutron floatingip-create hogehoge
Created a new floatingip:
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| fixed_ip_address    |                                      |
| floating_ip_address | 192.168.1.2                          |
| floating_network_id | d9eb9f00-dc2c-4fbf-89e9-70a79641e91d |
| id                  | 446da1ad-04f0-4fad-ab0a-c39667763c7c |
| port_id             |                                      |
| router_id           |                                      |
| status              | DOWN                                 |
| tenant_id           | e8ca6431d808494a839de2f18a26f10c     |
+---------------------+--------------------------------------+
===trace log===
2015-01-15 20:46:33.023 16435 INFO neutron.wsgi [req-b425d7c5-f3dd-41c2-ac45-b2e3251b0dfe None] 192.168.122.96 - - [15/Jan/2015 20:46:33] "POST /v2.0/floatingips.json HTTP/1.1" 201 487 0.077152
==========

As you can see from the trace log the code is 201, also, because of we are "creating" a floating IP, so I believe code 201 (created) is better than 200 (succeed).